Abstract
Simultaneous and continuous measurements of volumetric soil water content and soil solution electrical conductivity made using time domain reflectometry (TDR) sensors in an irrigated cornfield in the Yellow River basin, Inner Mongolia, China, were analyzed. The results are summarized as follows:
(a) Cumulative depth of water supplied to the root zone from a water table in spring and early summer of little rain was estimated to be about 80 mm, which may be traced to the irrigation water applied last autumn.
(b) When soil water moved upward from a water table to the soil surface during a period of little rain, soluble salts in the groundwater were transported through the root zone up to the soil surface.
(c) When basin irrigation was applied or a heavy rain occurred, part of the water applied flowed down quickly through macropores before much of the salt accumulated at the surface was dissolved in it. On the other hand, the rest of water in which the accumulated salt was fully dissolved moved slowly through smaller pores.
(d) When a large amount of water was applied to the soil surface, soluble salts in smaller pores moved downward quickly for a short distance and stayed at some lower depths. It can be reconfirmed from this result that small, intermittent applications are more effective for salt leaching than continuous flooding applications are.
